One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6)(7,10)(8,9)(11,12)(13,14,17,18)(15,19,24,26)(16,21,25,20)(22,23,28,27)(6,9)(7,11)(13,15)(14,19)(16,23)(17,24)(18,26)(20,22)(21,28)(25,27) involution — undirected(2,4)(13,16,17,25)(14,20,18,21)(15,22,24,28)(19,27,26,23)(6,9)(10,12)(13,16)(14,21)(15,23)(17,25)(18,20)(19,28)(22,26)(24,27) involution — undirected(5,7,8,11)(6,10,9,12)(13,14)(16,20)(17,18)(19,26)(21,25)(23,27)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.